Seeing my first ruby-throated hummingbird made skipping breakfast worthwhile. But when a growling stomach out-competes the raucous chatter of well-named chachalacas, it's time to eat. I bypass the taquerías to forage at the town's hot new foodie spot, McAllen Farmers Market.

My Tex-Mex-pectations would be surpassed many times while bird-watching in the Lower Rio Grande Valley.

Until recently, raw food would not inspire a cooking (or not-cooking) demo in the area ranked America's most obese in 2012. “We're building a healthier food culture and supporting the Valley's farmers,” says Deckard.

Nearby, I spot olive oil-based tamales, and James Canter, market co-founder and Culinary Institutes of America's 2012 King of Paella. He's preparing “carrots reunited” with carrot-top pesto, circled by figs and arugula. The veggies come from nearby Yahweh and Terra Preta farms, run by families who moved from Indiana and Utah.

Lard has become a four-letter word in McAllen, welcome news for residents and health-conscious snowbirds, a species whose range has expanded beyond beaches to “Texas tropics” border towns fringed with native sabal palms. Rhonda Gomez, who sells heirloom Lady Cream peas at the market, takes in winter lodgers at her McAllen “Bird's Nest.” Healthy meals, she says, “are essential for birders who are out in the field for 12 hours or more, watching shorebirds at dawn to raptors at twilight.”

Cathy and Bill Mauck, from Luray, Va., walk up to five miles a day. “He loves the tacos,” she says smiling, but the market fare is more suited to keeping up with the birds.

Trading deep-fried for farm-fresh isn't a big leap. Corn, squash, beans and other regional heritage ingredients can power meals free of lard, cheese and processed carbs.

Fliers advertise “Meet Your Farmer” mixers at Major Health Foods (owned by Lily Rambo, a “winter Texan”) and “Fooducation” events at the restored 1947 Cine El Rey Theatre. Having outgrown its downtown space, the McAllen market recently moved to the city's new library, a 2012 International Interior Design Association award-winner. The size of two-and-a-half football stadiums, this former Wal-Mart is now the nation's largest single-floor public library.

After numerous Midwestern farmers relocated to the snow-free “Magic Valley” a century ago, their visiting sun-starved relatives became the first winter Texans. Now snowbirds flock here for the subtropical weather and spectacular birds — 527 species, according to the South Texas Nature Co-op.

“Two major bird migratory flyways, the Central and Mississippi Flyways, lead millions of birds right through the Valley,” says Hagne. Winter birders watch for cloud-sweeping broad-winged hawks, endangered upland sandpipers and rare masked ducks alighting at streams, lagoons and resacas, ancient coils of riverbed left by retreating floodwaters.

In recent years, bird-watching has bolstered conservation efforts in the southern tip of Texas, which lost immense swaths of natural habitat to agriculture and urbanization since the railroad arrived in 1904. One successful community venture is the World Birding Center, a network of nine habitats between Roma and South Padre Island.

Birders bearing binoculars seek four dozen neotropical Rio Grande Valley specialties, so termed because they're found nowhere else in North America. These include the white-tipped dove, red-crowned parrot, golden-fronted woodpecker and ferruginous pygmy-owl. Other additions to birders' life lists include rarities such as the blue bunting, rose-throated becard and green-breasted mango.

Dave and Joyce Kuceyeski have spent seven winters in the Valley. The Canton, Ohio, couple, on the lookout for subtropical birds such as the great kiskadee, groove-billed ani and aplomado falcon, participate in hawk watches at Santa Ana National Wildlife Refuge.

Abutting the Rio Grande River, Santa Ana is a short ride southeast from McAllen. Established in 1943 to protect migratory birds, the refuge was part of a Mexican land grant traded for a fiddle and a new suit.

Since then, birders have observed 403 species finding sustenance in the refuge's lush vegetation that once covered the region. After spotting a clay-colored thrush, I follow a lakeside trail to a 40-foot observation tower and platforms anchoring a long rope-bridge. Atop the tower, I behold tree-top bird's-eye views in total silence except for birdcalls.

Back in McAllen, I stop at a World Birding Center, Quinta Mazatlan, a historic estate transformed into an urban bird sanctuary. Wandering through dense Tamaulipan thornscrub, I spot ringed kingfishers at a pond, buff-bellied hummingbirds sipping blooms and the town's brilliant official bird, green jays. On a terrace, people flit about with notepads. Bird checklists? No, they're planning an organic farm-to-table dinner.

As Mexican bluewing butterflies shimmer by, Mary Thorne, a seasonal volunteer from Sheboygan, Wis., points to a gossamer chrysalis. Inside, a caterpillar is turning into a butterfly. What a fitting symbol for this lively border town's transformation.

Robin Soslow, who covers outdoor and cultural travel, can be reached at rsoslow@gmail.com.